Electric switch



June 1% 1924.,

J. A. CRABTREE ELECTRIC SWITCH Filed Dec- 16 1919 3 Sheets-Sheet 1 June10 192%e 1,497J089 J. A. CRABTREE ELECTRIC SWITCH Filed Dec. 15 1919 3Sheets-Sheet 2 June 16 {1924.

J. A. CRABTREE ELECTRIC SWITCH Filed Dec. 16 1919 3- Sheets-Sheet 3Patented is re, 1924.

%T TT JOHN ASHWORTH. CRABTBEE, F YARDLEY, La

ELECTRIC SWITCH.

Application filed December 16, 1919. Serial No. 845,228.

To all whom it may concern:

Be it known that I, J oHiw ASHWORTH CRABTREE, a subject of the Kingdomof Great Britain, residing at Lynwood,

Clements Road, Yardley, in the county of \Varwick, England, engineer,have invented certain new and useful Improvements in or Relating toElectric Switches, of which the following is a specification.

This invention comprises certain improvements in or relating to electricswitches, of the type involving a pivoted operating member, a pivotedcontact arm or member, and a spring element operating between saidmembers adapted to enable the contact member to have a quick make orbreak action.

In the type of switch to which this invention refers, the spring elementis coupled pivotally to the operating member and contact member atpositions eccentrically of their respective axes, both extremities ofthe spring element being adapted to move in the action of closing oropening the switch. The present invention refers primarily to the stopprovision utilized for limiting the movements of the switch both in itsclosing and opening operations, and the present invention has for itspur ose to provide stop provision which is particularly Simple,effectual, and rigid. According to the present invention, in this typeof switch the contact arm or member is adapted to engage with stopprovision by an upward movement of the part of said contact arm ormember which comes into contact with said stop provision. By upwardmovement is meant movement in a direction away from the rear face of theswitch base; this being provided, the movement may occur at any angle.Advantageously the pivoted operating member above referred to is pivotedin the bridge, and the said bridge itself constitutes the stopprovision.

The present invention further refers primarily to the provisionincorporated in this type of switch for initially actuating the contactmember positively. According to the resent invention, this function isfulfilled throughthe medium of the spring eleelement may be adapted tofunction as a lever. In one arrangement the spring element is adapted toengage intermediately to its axes with a fulcrum portion, causing thement. In fulfilling this function the spring said spring element to berocked about said fulcrum to positively actuate the contact member. Inthis invention the expression sprrng elementiis intended to include anyprovision Involving a s ring, which prov1s1on is coupled pivotal y onthe one hand to the operating member and on the other hand to thecontact member. The spring itself may come into contact with the fulcrumportion, but I refer that a part other than the spring itself shouldexperience this engagement. To this end, in a case in which the springelement constitutes a telescopic sprin link a part of the telescopicmechanism is advantageously extended to intervene between the spring andthe fulcrum portion. Or I may incorporate be- .tween the two axes of thespring element a link or medium which is independent of the spring, butwhich fulfils the function of initially actuating the contact, memberpositively.

The present invention has further for its purpose to more effectively,securely and durably secure the pivot in the said bridge, and accordingto the present invention the pivot is retained by the screws utilizedfor fastening the bridge.

The present invention also refers to the porcelain or other base uponwhich the switch mechanism is mounted. Usually a 5 base of thischaracter is secured to any appropriate supporting part by screws whichpass through perforations in the base. It is the object of the presentinvention to reduce the dimensions of this type of base, otherconsiderations remaining the same. reduction in the overall dimensionsof such a base has a number of advantages. One advantage is that when anumber of the switches are mounted in proximity to each as other theycan be arranged in much more compact formation. The invention hasfurther the advantage that the possibility of breakage of the china baseis substantially reduced. me

With this object in View I adapt the base to be secured by screws orfastening members located externally of the perimeter of the base. Thesaid screws or fastenin members retain the base through the medium of mga metal part or parts which is or are anchored to the base by thefastening screws or members utilized for securing the bridge,

or the said parts may be integral with the bridge.

In order that this invention may be clearly understood and readilycarried into practice, reference may be had to the appended explanatorydrawings, upon which 1 Figure l is a sectional elevation of a switchconstructed according to the present Figure 4 is a section on line ABof- Figure 3.

Fig. 5 is a vertical sectional view, similar to Fig. 1, and showing theoperating member and the contact member in another position.

Fig. 6 is a detail sectional view showing a modified construction inwhich a separate plate or washer is located between the bridge and theswitch base, and forms a striking face for the contact arm.

Fig. 7 is a detail plan of the bridge.

Fig. 8 is a detail elevation showing the contact member and the contactcarrying member assembled.

Fig. 9 is a detail elevation of the contact carrying member at rightangles to Fig. 8.

In a convenient embodiment of the present invention, as applied to atumblenswitch, the tumbler operating member 1 is pivotally carried bythe bridge 2 and the contact member 3 is pivoted co-axially therewith.At a position below its fixed pivotal axis of movement the tumbleroperating member is pivotally connected to the upper extremity of thespring element, the lower extremity of which is pivotally connected tothe contact member at a position below the fixed axis of movement of thelatter. In operation, the axis of connection between the spring elementand the operating member is carried across the straight line extendingbetween the fixed axis of the operating member and the axis ofconnection between the spring element and the contact member.

A fixed fulcrum abutment 4 is incororated on each side of the springelement. in aid spring element is adapted to come into contact with thisabutment at a position intermediate its axes, so that the displacementof its upper axis by the operating member brings about a displacement ofits lower axis in the reverse direction, thereby positively displacingthe contact member initially, the subsequent displacement of the anemonecontact member occurring under the influence of the spring element,which, acting under compression, extends longitudinally.

The fulcrum abutment members i may comprise tongues depending orextending rearwardly from the bridge.

The spring element may comprise a U- shaped member 5, from each side ofthe transverse part of which a trunnion 6 extends, said trunnions beingaligned and located transversely to the plane of the U- member. Thetransverse part of the U-member may be provided rigidly or integrallywith a sleeve-like portion 7 in which a rod 8 is adapted to slide. Thisrod has at its upper extremity an eye through which extends a pivot 43by which said rod is pivotally coupled to the bifurcated lower extremityof the operating member.- The rod is encircled by a coiled compressionspring 9. The limbs of the U-member 5 constitute the parts which comeinto contact with the abutment members 4 depending from the bridgesocket 2.

The contact arm 3 also comprises a U- member, the transverse part ofwhich occurs at the point at which the circuit-closing element 10 iscarried. The limbs of the contact arm are extended in parallelism to thetrunnion axis of the spring element. Said arms are also extendedupwardly to the axis of the operating member. By this arrangement, asillustrated, when the switch is closed the movable contact surfaceandthe operating end of the hand lever occur on opposite sides of a planecontaining the axis of the contact member, and which plane is at rightangles to the plane of the base. The upwardly extending parts of thecontact arm are cranked outwardly from the parallel parts of the U toembrace the operating member. The perforations for the trunnions extendupwardly in the form of elongated slots beyond the crank formations sothat the trunnions can be assembled downwardly. Said trunnions areretained in said slots by the pressure of the sprin The contact member 3is stopped in both of its movements by the lower edge of the bridge 2,the abutment members 4 being adapted to depend from said lower edge inpositions intermediately to the limbs of the contact arm.

The circuit-closing element 10 is also in the form of a U-member stampedfrom sheet metal. The transverse part of said U-memher is cranked ordepressed to receive the extremity of the contact arm. The circuitclosing part thus involves a transverse portion parallel with thetransverse part of the contact arm, which transverse portion is at twopoints bent at right angles to embrace the end of the contact arm, andis then on each side of the contact arm bent through 180 degrees toextend away from the contact aeeaoea arm. The fixed contacts with whichsaid circuit-closing element is adapted to engage may thus internally ofthe element extend beyond the face of the transverse part thereof, thatis to say into recesses 15 formed between the side limbs and crankportion, withoutreducing the dimension (longitudinall of the contactarm) of the space with in t e same, which space may accommodate a springquick make and break action. These relative formations of thecircuitclosing element and contact arm serve to locate or to assist inlocating the circuitclosing element laterally in relation to the contactarm.

Between the cranked part of the circuitclosing element and the part ofthe contact arm which it embraces, a U-shaped layer of insulation 18 isincorporated. The transverse part of the contact arm is perforated toreceive a rivet 19, which rivet is adapted to pass through the layer ofinsulation and through a perforation 20 in the transverse part of thecircuit-closin element, which perforation last mentione exceeds thediameter of the rivet. On its face opposite to that which is in contactwith the insulating layer above mentioned the circuit-closing part isstepped around the perforation. This step is adapted to receive the base'of a cup 21, and to locate it in relation to the circuit-closing part.Alternatively the circuit-closing part ma be provided with aprojectionor projectlons adapted similarly to locate the cup. The saidcup is concentrically perforated at its base with a perforation of sizecorresponding with that in the circuit-closing part. This cup is adaptedto receive an annular body of insulatin material 22 such as micanite ora series 0 mica washers. 23 is a disc or layer of mica which may beplaced below the annular body 22. The body 22, the perforated cup, thecircuit-closing part, the layer of insulatin material, and the contactarm, are al clamped together by the rivet 19. As a result of thisclampin process the insulating media may be forced to substantially fillthe annular space around that part of the stem of the rivet which isencircled by the perforated cup and circuit-closing part. The head ofthe rivet may bear upon the disc 23 and body of insulating materialwithin the cup and the stem may be riveted or enlarged at the innersurface of the transverse part of the contact arm. Alternatively, therivet may be assembled from. within the contact arm and riveted at theexternal surface of the body of insulating material.

The cup or box-like member 21 may obviously be of circular, oval,square, rectangular, or other configuration.

The bridge 2 involves a socket '2 and is provided with the usual cars 24which are perforated for attachment to the china base 25. I adapt thepivot pin 26 to pass through the socket and to extend at bothextremities in contiguit with the ears. The fastening of the bridge isefiected by the use of stems 27, which may have heads (not shown)forming abutments for the ends of the pivot pin 26, or which (as shown)are perforated transversely to re-- 'carry the switch cover, but I may,as for instance in a case in which this screw thread is unnecessary,emplo a bridge which does not involve a socket 0 this character.

In Fig. 6 of the drawing, I show a modified construction in which aseparate plate or washer 41 is located between the bridge 2 and thebase, which plate or washer forms striking faces or shoulders 41' forthe contact arm 3.

The base 25 may be substantially of octagonal form, alternate faces 36being curved concentrically and intermediate faces 32 being in planes atright angles to each other. Ata mid-point in each of two opposite ofthese intermediate faces, indentations or semi-circular groovings 38 areprovided to accommodate the fastening screws. Below each ear 24 of thebrid e a plate 10 is secured. Said plate is per orated for the bridgefastening screw 27 to pass therethrough, and said plate or the bridgemay have projecting abutments adapted by engagement with the bridge orsaid plate or the base, respectively, to prevent rotary deran ement ofsaid plate. The said plate extends outwardly and is perforated coaxiallyor a proximately co-axially with the semi-circu ar groove 38 in thebase. The fastening screw for the switch passes through thisperforation, which may be countersunk. The plate 40 may thus constitutean earthing or ground connecting memher. It will be seen that the partof the switch 1 which is manipulated by the hand, is by virtue of theplate 40 in electrical connection with the switch fastening screw whichis located in the groove 38, and passes into the conduit box or groundedpart. In cases in which two switches are located side by side, a singlefastening screw may be utilized to secure the adjacent sides of the saidswitches. These sides may be located in contact with each other so thatthe semi-circular groovings together form a perforation. I A singleplate extends from operating member and a pivoted rocking member, bothadapted to oscillate about one and the same axis, and a spring adaptedto enable the movable contact to have a quick make and break action, byvirtue of a toggle of which the said operating member forms one element,both axes of the other arm of which toggle are adapted in the action ofclosing or opening the switch to .move in arcs, the mean points of whichare substantially nearer to the back of the switch base than is thepivot or axis of the said operating and rocking members, and in which,when the switch is closed, the movable contact surface and that end ofthe operating lever which is adapted to be actuated manually, occur onopposite sides of a plane containin the axis of movement of the saidoperating and rocking members, and which plane is at right angles to theback of the base, the arrangement being such that in the operation ofopening the switch the said end of the operating lever passes throughthe said plane. Y

2. In an electric switch, a swinging contact element comprising acarrier member and a contact member, insulating material between saidmembers, a rivet securing said members together and passing through saidinsulating material, said contact member having shoulders spaced fromopposite sides of said carrier member, and said insulating materialhaving abutting end portions bearing against the said shoulders, a cupfitted in a recess in said contact member, and an insulator in thehollow side of said cup, the said rivet also extending through saidinsulator and cup.

3. In an electric switch, an insulating base, a plate thereon, a bridgebearing on said plate and by which the movable members of the switch arecarried, and' common fastening means securing said base, plate andbridge together.

t. In an electric switch, an insulating base, a plate thereon, a bridgebearing on said plate and by which the movable members of the switch arecarried, and common fastening means securing said base, plate and bridgetogether, said base having grooves in its sides and said plate havingopenings over said grooves, said grooves and openings being arranged toreceive fastening screws for the switch.

5. ln an electric switch, an insulating base, a plate thereon, a bridgebearing on said plate and by which the movable members of the switch arecarried, common fastening means securing said base, plate and bridgetogether, and a pivot for the movable switch members and engaged withthe bridge and also engaged with the said common fastening means.

6. An electric switch comprehending in combination, an operating membermovable about a permanently stationaryaxis, a contact member alsomovable about a permanently stationary axis, a floating member pivotallyconnected to the operating member at a point eccentric to the axis ofthe latter and to the contact member at a point eccentric to the axis ofthe latter, resilient provision adapted to displace the toggle in eitherdirection after it has passed its dead centre, and abutment provisionwith which said floating member is adapted to engage.

7. In an electric switch, an insulating base, a bridge, a pivot-mountedin said bridge, and means for securing the bridge to the base whichmeans also retain the said pivot.

In witness whereof l have hereunto set my hand.

JUHN ASHWQRTH CRABTREE.

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